Yes, fortunately rifles, in general terms, are not subjected to great deals of moisture. However undoubtedly there is some that will travel under the bbl nut where it can become a host for galvanic action. Also copper on various steels and under various conditions has shown to induce stress cracking/embrittlement. There are a handful of mechanisms by which this occurs.
The entire potential for for any of this can be avoided using nickel based antiseize, so I guess you can use whatever you like, but it's cheap insurance.

and I guess I should add that I now just use a dab of white lithium grease for assembly. Just enough to prevent galling.